This invention relates to a method of determining masses of absorbing components of a sample in a test volume, using electromagnetic radiation in the infrared region of the spectrum passing in separate beams through both the test volume and a reference volume, and both the test beam and the reference beam being fed to a detector, alternating periodically, and the masses to be measured being obtained from the differences in radiation intensity. The time constant of the detector used is smaller by at least one order of magnitude than the period of alternation between test beam and reference beam.
Furthermore, the invention relates also to a device for implementation of this method.